The deposition by cathode sputtering of anti-friction layers of molybdenum sulphide is already known. Thus, for example, Spalvins (ASLE Transactions 14, (4), 267-274 (1971); NASA TM X-71742 (1975) describes the deposition of such layers on highly polished metal surfaces (5.times.10.sup.-2 .mu.m surface roughness) by using the technique known as radio frequency sputtering and DC polarization. Spalvins used a target of pure MoS.sub.2 and worked under conditions enabling self-lubricating, amorphous or microcrystalline adherent deposits to be obtained on various substrates (Ni, Au, Ag, Co, Mo, W, Ti, Al, steels, glass and certain synthetic resins), at a rate of about 0.015 .mu.m per minute. Such films had coefficients of friction (measured in a high vacuum by means of the "disc and ball" device described hereinafter) of the order of 0.03 to 0.04 for thicknesses of 0.2 to 0.65 .mu.m. However, this process has certain disadvantages. Thus, on account of the low efficiency of the process it is virtually impossible to obtain deposits having a thickness substantially greater than 0.5 to 1 .mu.m, and it has a tendency to form excrescences of MoS.sub.2 on the uneven parts of the substrates, which means that the substrates to be plated have to be extremely highly polished if industrially usable anti-friction coatings are to be obtained. Furthermore, the structure of the deposits does not provide very favorable wear resistance properties, especially in the presence of moisture. Finally, and the reason for this is unknown, the deposits obtained by the Spalvins method do not adhere to copper and bronze, which is a serious disadvantage in the case of anti-friction coatings intended for bearings or small mechanical parts, often manufactured from brass or bronze.